It is known in the window and door fabrication industry to treat large glass sheets for use in the fabrication of windows and doors with a material that provides specified light transmission or reflection properties. One common treatment applies a layer of material uniformly across a glass sheet to provide lower radiation transmissivity. When such glass is used in fabricating a insulating glass unit (IGU) having multiple spaced apart lites, the low transmissivity layer can be located on an outside of the glass unit to lower the tendency of the sun's radiation to heat a building interior. On other insulating glass units, the low transmissive layer can be placed on the inside of the IGU to reduce the amount of heat radiation exiting the building. In known applications, a silver containing compound is uniformly applied to a surface of glass sheets from which IGU lites (or panes) are cut to achieve such properties.
Experience with fabricating window or door lites from large sheets of glass indicate it is preferable to remove radiation reflecting or transmitting material before scoring the glass for breakout into smaller pane sized lites. If these coatings are not first removed, the glass tends to break, chip or otherwise become damaged in the region of the glass scoring. If the coating is removed at a processing station downstream from the cutting station, the probability of damage is increased due to handling of the glass sheets. The coating is removed in a region of the glass to which sealant is applied to promote adhesion properties of the sealant.
One prior art patent that addresses the problems of removing such coating material is U.S. Pat. No. 5,449,312 to Lisec. This patent discloses a process for simplifying the cutting of a glass sheet with the help of a cutting tool and the removal of a coating applied on a glass sheet with the help of a grinding tool.